Process for the preparation of 1,4-disubstituted-5(4H)-tetrazolinones

Abstract: 1,4-Disubstituted-5(4H)-tetrazolinones of the formula (I) (wherein R¹, R² and R³ have the meanings given in the specification), which are known to be useful as herbicides, can be obtained in very good yields by reacting the corresponding 1-substituted-5(4H)-tetrazolinones with the corresponding carbamoyl chlorides in the presence of 4-dimethylaminopyridine.

Description: The present invention relates to a novel process for the production of known 1,4-disubstituted-5(4H)-tetrazolinones which can be utilized, for example, as agricultural chemicals. Regarding the synthesis of tetrazolinones of the type of general formula (I) below, there is generally known, for example, a process wherein a tetrazolinone compound represented by the general formula: wherein M represents hydrogen or an alkali metal selected from the group consisting of Li, Na and K etc., is reacted with a carbamoyl chloride (U.S. Patent 4,618,365). Concerning the above-mentioned reaction, when use is made, as M, of a hydrogen atom, it is preferably carried out in the presence of a suitable acid-acceptor such as pyridine, trialkylamine and the like. Further, in this reaction, use may be made, as suitable solvents, of acetone, acetonitrile, toluene, chloroform and the like. The essential reaction of a triazolinone compound of formula (II) below with a carbamoyl chloride of formula (III) below, in the presence of an inert solvent and optionally in the presence of an acid binder, to produce 1,4-disubstituted 5(4H)-tetrazolinones of the type of general formula (I) below - in average yields of about 70 % of theory -, is also described in certain intermediate prior art documents (EP-A-0 612 735, EP-A-0 578 090, EP-A-0 572 855, EP-A-0 571 855 and EP-A-0 571 854), 4-dimethylamino-pyridine (4-DMAP) being listed in each of these documents as a possible acid-binder amongst many others, where the amount of 4-DMAP used is not specified. However, such known process produces, in addition to the desired tetrazolinones, the isomeric compounds represented by the following general formula (A): (referred to as "O-carbamoyl compounds"hereinafter) as by-products and the production rate of such by-products sometimes turns out to be as much as one third of the production rate of the desired compounds (Figs. 1 to 5). The O-carbamoyl compound by-products do not exhibit such herbicidal activity as shown by the aimed N-carbamoyl tetrazolinones, while these O-carbamoyl compounds as such are chemically unstable, i.e. they are readily hydrolyzable by aqueous acids and alkali so that the separation and removal procedure of O-carbamoyl compounds from the desired N-carbamoyl products (I) gives rise to a substantial technical difficulty. Thus the known process has a serious inherent defect in view of reaction procedure and reaction efficiency. To solve the above-mentioned technical problem, there has now been found a process - with two process variants (a) and (b) - for selectively producing 1,4-disubstituted-5(4H)-tetrazolinones of the general formula (I), wherein R 1 represents C 1-12 alkyl, C 1-6 haloalkyl, C 2-8 alkoxyalkyl, C 2-8 alkylthioalkyl, C 3-8 cycloalkyl, C 3-8 alkenyl, C 3-8 haloalkenyl, C 3-8 alkynyl, or a group represented by the general formula wherein Ar represents unsubstituted phenyl, or a phenyl group having a substituent or substituents optionally selected from the group consisting of halogen C 1-4 alkyl, C 1-4 haloalkyl, C 1-4 alkoxy,C 1-4 haloalkoxy, C 1-4 alkylthio, C 1-4 haloalkylthio, C 1-4 alkoxy-carbonyl, carboxy, optionally substituted phenoxy, optionally substituted heterocyclyl-oxy, methylene dioxy, halomethylene dioxy, ethylene dioxy, haloethylene dioxy, cyano, nitro and -NR 5 R 6 ; or Ar represents unsubstituted naphthyl, or a substituted naphthyl group having a substituent or substituents optionally selected from the group consisting of halogen C 1-4 alkyl, C 1-4 haloalkyl, C 1-4 alkoxy, C 1-4 haloalkoxy, C 1-4 alkylthio, C 1-4 haloalkylthio, C 1-4 alkoxy-carbonyl, carboxyl, optionally substituted phenoxy, optionally substituted heterocyclyl-oxy, methylene dioxy, halomethylene dioxy, ethylene dioxy, haloethylene dioxy, cyano, nitro and -NR 5 R 6 ; or Ar represents a five- to seven-membered heterocyclic ring or their benzologues or their substituted derivatives having a substituent or substituents optionally selected from the group consisting of halogen, C 1-4 alkyl, C 1-4 haloalkyl, C 1-4 alkoxy, C 1-4 haloalkoxy, C 1-4 alkylthio, C 1-4 haloalkylthio, C 1-4 alkoxy-carbonyl, carboxy, optionally substituted phenoxy, optionally substituted heterocyclyl-oxy, methylene dioxy, halomethylene dioxy, ethylene dioxy, haloethylene dioxy, cyano, nitro and -NR 5 R 6 ; R 4 represents hydrogen or C 1-4 alkyl, R 5 and R 6 may be the same or different and represent hydrogen or C 1-4 alkyl, and n represents 0, 1, 2 or 3; and R 2 and R 3 each independently represents methyl, ethyl, n-propyl, isopropyl, n-(sec-,iso-, or tert-)butyl, n-pentyl, n-hexyl, trifluoromethyl, difluoromethyl, 2-chloroethyl, 2-fluoroethyl, 2,2,2-trifluoroethyl, 3-fluoropropyl, perfluoropropyl, perfluorohexyl, 2-methoxyethyl, ethoxymethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-methylthioethyl, 3-methylthiopropyl, 2-ethylthioethyl, allyl, 2-(3-, 4-)butenyl, hexenyl, 3-chloroallyl, propargyl, methoxy, ethoxy, n-propoxy, isopropoxy, 3-chloroallyloxy, cyclopropyl, cyclopentyl, cyclohexyl, optionally substituted phenyl or benzyl, (wherein said substituents may be optionally selected from the group consisting of fluorine, chlorine, bromine, methyl, ethyl, n-propyl, isopropyl, tert-butyl, trifluoromethyl, methoxy, ethoxy, isopropoxy, difluoromethoxy, trifluoromethoxy, methylthio, ethoxy, isopropoxy, difluoromethoxy, trifluoromethoxy, methylthio, ethylthio, trifluoromethylthio, 2,2,2-trifluoroethylthio, cyano and nitro), or R 2 and R 3 together with the adjacent nitrogen atom may form piperidino, 2,6-dimethylpiperidino, morpholino, 2,6-dimethylmorpholino, thiomorpholino, 2,3-dihydroindolyl or perhydroindolyl, which process comprises (a) reacting a compound represented by the general formula (II), wherein R 1 has the same meaning as mentioned above, with a compound represented by the general formula (III) wherein R 2 and R 3 have the same meanings as mentioned above, in the presence of a catalytic (sub-stoichiometric) amount of 4-dimethylamino-pyridine and optionally in the presence of a diluent and of an additional acid-binder selected from the group consisting of inorganic bases (such as carbonates and bicarbonates of alkali metals) and organic bases (such as tertiary amines, pyridines, DABCO and DBU), at a temperature of from +15°C to +150°C, or (b) reacting a compound represented by the above-mentioned general formula (II) with a compound represented by the above-mentioned general formula (III), optionally in the presence of a diluent and of an acid-binder other than 4-dimethylamino-pyridine (as defined under process variant (a) above), to obtain a mixture consisting of a tetrazolinone represented by the above-mentioned general formula (I) and a compound represented by the general formula (IV), wherein R 1 , R 2 and R 3 have the same meanings as mentioned above, (first step) followed by reacting said obtained mixture with a catalytic (sub-stoichiometric) amount of 4-dimethylamino-pyridine, optionally in the presence of a diluent, at a temperature of from +15°C and +150°C, thereby effecting conversion of the compound(s) of formula (IV) to the desired isomeric compound(s) of formula (I) (second step), employing in both process variants (a) and (b) the 4-dimethylamino-pyridine as catalyst in amounts of from 0.01 to 0.5 mols per mol of the compound of formula (II). The production process according to the present invention has surprisingly been found to be able to selectively prepare the aimed tetrazolinones represented by the general formula (I) in a high yield, by either reacting a compound represented by the general formula (II) with a compound represented by the general formula (III) in the presence of catalytic amounts of 4-dimethylamino-pyridine, or by reacting the above-mentioned starting materials (II) and (III) according to a conventional procedure, followed by reacting the resulting mixture of isomeric compounds of formulas (I) and (IV) with catalytic amounts of 4-dimethylamino-pyridine, thereby effecting a 1,3-migration of the carbamoyl substituent, from O to N. The 4-dimethylamino-pyridine to be employed in the production process according to the present invention can be used as acid-acceptor and catalyst, or as catalyst together with another acid-acceptor as stated afterwards. The process according to the present invention is an excellent process that can be applied to the production of such a wide scope of tetrazolinone compounds as represented by the general formula (I) and has been found to be the most suitable one for the production of the aimed tetrazolinones in an industrial scale. A preferred group of 1,4-disubstituted-5(4H)-tetrazolinones, to be produced according to the present invention are those compounds of formula (I), wherein R 1 represents methyl, ethyl, n-propyl, isopropyl, n-(sec-, iso-, or tert-)butyl, n-hexyl, trifluoromethyl, difluoromethyl, chlorodifluoromethyl, 2,2,2-trifluoroethyl, perfluoropropyl, perfluorohexyl, methoxyethyl, ethoxymethyl, ethoxyethyl, propoxyethyl, butoxyethyl, methylthioethyl, methylthiomethyl, methylthiopropyl, ethylthiomethyl, ethylthioethyl, propylthioethyl, butylthioethyl, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, allyl, chloroallyl, butenyl, hexenyl, propargyl, or a group represented by the general formula wherein Ar represents unsubstituted phenyl or a phenyl group having a substituent or substituents optionally selected from the group consisting of fluorine, chlorine, bromine, methyl, ethyl, propyl, butyl, difluoromethyl, chlorodifluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, methoxy, ethoxy, propoxy, butoxy, difluoromethoxy, chlorodifluoromethoxy, trifluoromethoxy, 2,2,2-trifluoroethoxy, methylthio, ethylthio, propylthio, difluoromethylthio, trifluoromethylthio, 2,2,2-trifluoroethylthio, dimethylamino, diethylamino, methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, carboxy, phenoxy, optionally substituted heterocyclyl-oxy, (wherein the hetero ring of said heterocyclyl-oxy is selected from the group consisting of imidazole, pyrazole, thazole, oxazole, isoxazole, benzoxazole, thiazole, isothiazole, benzothiazole, oxadiazole, thiadiazole, tetrazole, pyridine, quinoline, isoquinoline, pyrimidine, pyridazine, pyrazine, quinazoline, quinoxaline, triazine, thiophene, benzothiophene, furan and benzofuran), methylenedioxy, difluoromethylenedioxy, ethylenedioxy, chlorodifluoroethylenedioxy, difluoroethylenedioxy, trifluoroethylenedioxy, tetrafluoroethylenedioxy, cyano and nitro; or Ar represents unsubstituted naphthyl or a substituted naphthyl group having a substituent or substituents optionally selected from the group consisting of fluorine, chlorine, bromine, methyl, ethyl, propyl, butyl, difluoromethyl, chlorodifluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, methoxy, ethoxy, propoxy, butoxy, difluoromethoxy, chlorodifluoromethoxy, trifluoromethoxy, 2,2,2-trifluoroethoxy, methylthio, ethylthio, propylthio, difluoromethylthio, trifluoromethylthio, 2,2,2-trifluoroethylthio, dimethylamino, diethylamino, methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, carboxy, phenoxy, optionally substituted heterocyclyl-oxy, (wherein the hetero ring of said heterocyclyl-oxy is selected from the group consisting of imidazole, pyrazole, triazole, oxazole, isoxazole, benzoxazole, thiazole, isothiazole, benzothiazole, oxadiazole, thiadiazole, tetrazole, pyridine, quinoline, isoquinoline, pyrimidine, pyridazine, pyrazine, quinazoline, quinoxaline, triazine, thiophene, benzothiophene, furan and benzofuran), methylenedioxy, difluoromethylenedioxy, ethylenedioxy, chlorodifluoroethylenedioxy, difluoroethylenedioxy, trifluoroethylenedioxy, tetrafluoroethylenedioxy, cyano and nitro; or Ar represents an unsubstituted or substituted five- or six-membered heterocyclic ring and their benzologues, wherein said hetero ring is selected from the group consisting of imidazole, pyrazole, triazole, oxazole, isoxazole, benzoxazole, thiazole, isothiazole, benzothiazole, oxadiazole, thiadiazole, tetrazole, pyridine, quinoline, isoquinoline, pyrimidine, pyridazine, pyrazine, quinazoline, quinoxaline, triazine, thiophene, and furan), having a substituent or substituents optionally selected from the group consisting of fluorine, chlorine, bromine, methyl, ethyl, propyl, butyl, difluoromethyl, chlorodifluoromethyl, trifluoromethyl, 2,2,2-trifluoroethyl, methoxy, ethoxy, propoxy, butoxy, difluoromethoxy, chlorodifluoromethoxy, trifluoromethoxy, 2,2,2-trifluoroethoxy, methylthio, ethylthio, propylthio, difluoromethylthio, trifluoromethylthio, 2,2,2-trifluoroethylthio, dimethylamino, diethylamino, methoxycarbonyl, ethoxycarbonyl, butoxycarbonyl, carboxy, phenoxy, optionally substituted heterocyclyl-oxy, (wherein the hetero ring of said heterocyclyl-oxy is selected from the group consisting of imidazole, pyrazole, triazole, oxazole, isoxazole, benzoxazole, thiazole, isothiazole, benzothiazole, oxadiazole, thiadiazole, tetrazole, pyridine, quinoline, isoquinoline, pyrimidine, pyridazine, pyrazine, quinazoline, quinoxaline, triazine, thiophene, benzothiophene, furan and benzofuran), methylenedioxy, difluoromethylenedioxy, ethylenedioxy, chlorodifluoroethylenedioxy, difluoroethylenedioxy, trifluoroethylenedioxy, tetrafluoroethylenedioxy, cyano and nitro, R 4 represents hydrogen or methyl, n is an integer of 0, 1 or 2, and R 2 and R 3 each independently represents methyl, ethyl, n-propyl, isopropyl, n-(iso-, sec-, tert-)butyl, trifluoromethyl, difluoromethyl, 2-methoxyethyl, ethoxymethyl, 2-ethoxyethyl, 2-methylthioethyl, allyl, 2-butenyl, 3-chloroallyl, propargyl, methoxy, ethoxy, n-propoxy, cyclopropyl, cyclopentyl, cyclohexyl, or an optionally substituted phenyl or benzyl, having a substituent or substituents selected from the group consisting of fluorine, chlorine, bromine, methyl, ethyl, n-propyl, isopropyl, tert-butyl, trifluoromethyl, methoxy, ethoxy, trifluoromethoxy, methylthio, cyano and nitro, or R 2 and R 3 together with the adjacent nitrogen atom may form piperidino, morpholino, thiomorpholino, 2,3-dihydroindolyl or perhydroindolyl. The compounds represented by the general formula (II) and employed as starting materials in the production process according to the present invention can be obtained by the processes disclosed in J. Am. Chem. Soc., vol. 81, pp. 3076-3079 (1959); J. Org. Chem. vol. 45, pp. 5130-5136 (1980) and Japanese Patent Application No. Hei 5-212153. The compounds represented by the general formula (III) are well known in organic chemical field. The above-mentioned general definitions of radicals or explanations, or those mentioned in preferred ranges, are applicable in a corresponding manner to the end products (I) and to the starting materials (II) and (III) and "intermediates" (IV). These definitions of radicals may be combined as desired with one another, in other words also between the particular preferred ranges. Representative 1-substituted-5(4H)-tetrazolinones of the formula (II) include the following compounds: 1-phenyl-5-(4H)-tetrazolinone, 1-(3,5-dichlorophenyl)-5(4H)-tetrazolinone, 1-(2-chlorophenyl)-5(4H)-tetrazolinone, 1-(2-chloro-3-methylphenyl)-5(4H)-tetrazlinone, 1-(3,5-dichlorophenyl)-5(4H)-tetrazolinone, 1-(2-chloro-4-trifluoromethylphenyl)-5(4H)-tetrazolinone, 1-methyl-5(4H)-tetrazolinone, 1-benzyl-5(4H)-tetrazolinone, 1-(3,4-tetrafluoroethylenedioxyphenyl)-5(4H)-tetrazolinone, 1-(2-chloro-5-pyridylmethyl)-5(4H)-tetrazolinone, 1-ethyl-5(4H)-tetrazolinone, 1-n-propyl-5(4H)-tetrazolinone, 1-isopropyl-5(4H)-tetrazolinone, 1-tert-butyl-5(4H)-tetrazolinone, 1-cyclopropyl-5(4H)-tetrazolinone, 1-cyclopentyl-5(4H)-tetrazolinone, 1-cyclohexyl-5(4H)-tetrazolinone, 1-(2,2,2-trifluoroethyl)-5(4H)-tetrazolinone, 1-(2-methoxyethyl)-5(4H)-tetrazolinone, 1-(2-ethylthioethyl)-5(4H)-tetrazolinone, 1-(2-methylthioethyl)-5(4H)-tetrazolinone, 1-allyl-5(4H)-tetrazolinone, 1-(3-chloroallyl)-5(4H)-tetrazolinone, 1-propargyl-5(4H)-tetrazolinone, 1-(2-fluorophenyl)-5(4H)-tetrazolinone, 1-(3-chlorophenyl)-5(4H)-tetrazolinone, 1-(3-trifluoromethylphenyl)-5(4H)-tetrazolinone, 1-(4-trifluoromethylphenyl)-5(4H)-tetrazolinone, 1-(4-chlorophenyl)-5(4H)-tetrazolinone, 1-(2-methylphenyl)-5(4H)-tetrazolinone, 1-(3-methylphenyl)-5(4H)-tetrazolinone, 1-(4-methylphenyl)-5(4H)-tetrazolinone, 1-(2-methoxyphenyl)-5(4H)-tetrazolinone, 1-(4-methoxyphenyl)-5(4H)-tetrazolinone, 1-(4-trifluoromethoxyphenyl)-5(4H)-tetrazolinone, 1-(4-trifluoromethylthiophenyl)-5(4H)-tetrazolinone, 1-(3-propylphenyl)-5(4H)-tetrazolinone, 1-(4-tert-butylphenyl)-5(4H)-tetrazolinone, 1-(2,4-dichlorophenyl)-5(4H)-tetrazolinone, 1-(2,6-dichlorophenyl)-5(4H)-tetrazolinone, 1-(2-chloro-6-methylphenyl)-5(4H)-tetrazolinone, 1-(3-chloro-4-trifluoromethylphenyl)-5(4H)-tetrazolinone, 1-[4-(2,4-dichlorophenoxy)phenyl]-5(4H)-tetrazolinone, 1-[4-(2-chloro-4-trifluoromethylphenoxy)phenyl]-5(4H)-tetrazolinone, 1-[4-(2,6-dichloro-4-trifluoromethylphenoxy)phenyl]-5(4H)-tetrazolinone, 1-(3-phenoxyphenyl)-5(4H)-tetrazolinone, 1-(3,4-difluoromethylenedioxyphenyl)-5(4H)-tetrazolinone, 1-[4-(3,5-dichloropyridin-2-yloxy)-phenyl]-5(4H)-tetrazolinone, 1-[3,5-bis(trifluoromethyl)phenyl]-5(4H)-tetrazolinone, 1-(2-cyanophenyl)-5(4H)-tetrazolinone, 1-(4-chloro-2-fluoro-5-isopropoxyphenyl)-5(4H)-tetrazolinone, 1-[4-chloro-2-fluoro-5-(methoxycarbonyl)methoxyphenyl]-5(4H)-tetrazolinone, 1-[4-chloro-2-fluoro-5-(n-pentyloxycarbonyl)methoxyphenyl]-5(4H)-tetrazolinone, 1-(7-fluoro-4-ethoxy-2H-1,4-benzoxazine-3(4H)-one-6-yl)-5(4H)-tetrazolinone, 1-(7-fluoro-4-propargyl-2H-1,4-benzoxazine-3(4H)-one-6-yl)-5(4H)-tetrazolinone, 1-(6-fluoro-4-propargyl-2H-1,3-benzoxazole-2-one-5-yl)-5(4H)-tetrazolinone, 1-(6-fluoro-4-propargyl-2H-1,3-benzothiazole-2-one-5-yl)-5(4H)-tetrazolinone, 1-[4-chloro-2-fluoro-5-(methanesulphonylamino)phenyl]-5(4H)-tetrazolinone, 1-(3-tert-butylisoxazole-5-yl)-5(4H)-tetrazolinone, 1-(5-tert-butylisoxazole-3-yl)-5(4H)-tetrazolinone, 1-(5-tert-butyl-1,3,4-thiazole-2-yl)-5(4H)-tetrazolinone, 1-(5-trifluoromethyl-pyridine-2-yl)-5(4H)-tetrazolinone, 1-(3-chloro-5-trifluoromethyl-pyridine-2-yl)-5(4H)-tetrazolinone, 1-(2-chloroethyl)-5(4H)-tetrazolinone, 1-(2-fluoroethyl)-5(4H)-tetrazolinone, and 1-3(fluoropropyl)-5(4H)-tetrazolinone. Representative carbamoyl chlorides of the formula (III) include the following compounds: N,N-dimethyl carbamoylchloride, N,N-diethyl carbamoylchloride, N-ethyl-N-methyl carbamoylchloride, N-ethyl-N-n-propyl carbamoylchloride, N-ethyl-N-isopropyl carbamoylchloride, N-ethyl-N-iso-butyl carbamoylchloride, N-ethyl-N-sec-butyl carbamoylchloride, N-ethyl-N-tert-butyl carbamoylchloride, N-ethyl-N-cyclopentyl carbamoylchloride, N-ethyl-N-cyclohexyl carbamoylchloride, N,N-di-n-propyl carbamoylchloride, N-n-propyl-N-isopropyl carbamoylchloride, N-n-propyl-N-cyclopentyl carbamoylchloride, N-n-propyl-N-cyclohexyl carbamoylchloride, N,N-di-isopropyl carbamoylchloride, N-isopropyl-N-cyclopentyl carbamoylchloride, N-isopropyl-N-cyclohexyl carbamoylchloride, N,N-di-n-butyl carbamoylchloride, N-n-butyl-N-cyclopropyl carbamoylchloride, N,N-diallyl carbamoylchloride, N,N-dipropargyl carbamoylchloride, N-methoxy-N-n-propyl carbamoylchloride, N-ethoxy-N-n-propyl carbamoylchloride, N-methyl-N-phenyl carbamoylchloride, N-ethyl-N-phenyl carbamoylchloride, N-n-propyl-N-phenyl carbamoylchloride, N-isopropyl-N-phenyl carbamoylchloride, N-isopropyl-N-(3-methylphenyl) carbamoylchloride, N-isopropyl-N-(4-chlorophenyl) carbamoylchloride, N-isopropyl-N-(4-fluorophenyl) carbamoylchloride, N-methyl-N-(2-trifluoromethylphenyl) carbamoylchloride, N-methyl-N-(3-trifluoromethylphenyl) carbamoylchloride, N-isopropyl-(3-trifluoromethylphenyl) carbamoylchloride, N-isopropyl-(3-n-propylphenyl) carbamoylchloride, 4-chlorocarbonyl-morpholine, 4-chlorocarbonyl-thiomorpholine, 4-chlorocarbonyl-2,6-dimethylmorpholine, 1-chlorocarbonyl-piperdine, 1-chlorocarbonyl-2,6-dimethylpiperidine, 1-chlorocarbonyl-2,3-dihydroindole, and 1-chlorocarbonyl-perhydroindole. Process variant (a) according to the invention for the production of the compounds of formula (I) is preferably carried out using diluents. Representative suitable diluents include liquid aliphatic, cycloaliphatic and aromatic, optionally chlorinated, hydrocarbons such as benzene, toluene, xylene, chloroform, chlorobenzene, and the like; ethers such as dioxane, dimethoxyethane (DME), tetrahydrofuran (THF), and the like; ketones such as, for example, acetone, methyl ethyl ketone, methyl isopropyl ketone, methyl iso-butyl ketone, and the like; nitriles such as acetonitrile, propionitrile, and the like; esters such as, for example, ethyl acetate, and the like; and liquid bases such as, for example, pyridine, and the like. Process variant (a) according to the invention is carried out in the presence of 4-dimethylamino-pyridine, which functions not only as acid-binder but also as catalyst. If 4-dimethylamino-pyridine is employed in only catalytic (sub-stoichiometric) amounts, then process variant (a) is carried out in the presence of an additional acid-binder (in at least stoichiometric amounts). Representative additional acid-binders include inorganic bases such as, for example, carbonates and bicarbonates of alkali metals such as, for example, sodium hydrogen carbonate, potassium hydrogen carbonate, sodium carbonate, potassium carbonate, and the like; and, as organic bases may be mentioned tertiary amines and pyridines such as, for example, triethylamine, 1,1,4,4-tetramethylethylenediamine (TMEDA), N,N-dimethylaniline, N,N-diethylaniline, pyridine, 1,4-diazabicyclo[2,2,2]octane (DABCO), and 1,8-diazabicyclo-[5,4,0]undec-7-ene (DBU). As stated above, the process variant (a) is carried out in general at a temperature of from +15°C to +150°C, preferably from +50°C to +130°C. Further, the reaction is preferably carried out under normal pressure, although it is also possible to employ a higher or reduced pressure. In carrying out process variant (a) according to the invention, the desired compounds of the formula (I) can be obtained in high yields by reacting of about 0.8 to 1.5 mols of the compound of the formula (III) per mol of the compound of the formula (II), in the presence of about 0.01 to about 0.5 mols of 4-dimethylamino-pyridine as well as 0.3 to 1.5 mols of an additional acid binder. In carrying out the process variant (a) with the use of 4-dimethylamino-pyridine as sole acid-binder, it may be used in the amount of from about 0.8 to about 1.5 mols, including the aimed catalytic amount. Process variant (b) according to the invention is preferably carried out using diluents. Solvents which are suitable for this purpose are virtually the same organic solvents as have been mentioned above in connection with the description of process variant (a) according to the invention. The first step of process variant (b) is preferably carried out in the presence of an acid acceptor. Acid-binding agents which are suitable for this purpose are the same as have been mentioned above in connection with the description of process variant (a) according to the invention. In the second step of process variant (b), there must be employed 4-dimethylamino-pyridine as catalyst for the isomerization reaction (carbamoyl-migration). In general, the process variant (b) is carried out at a temperature of from 15°C to 150°C, preferably from 50°C to 130°C. Further, the reaction is preferably carried out under normal pressure, although it is also possible to employ a higher or reduced pressure. When the above-mentioned process variant (b) according to the present inventioin is carried out, the compounds represented by the general formulae (II) and (III), respectively, are reacted in approximately equimolar amounts, followed by reacting the thus prepared mixture of a compound represented by the general formula (I) and its isomer represented by general formula (IV) with about 0.01 to about 0.5 mols of 4-dimethylamino-pyridine as catalyst, so as to obtain the desired tetrazolinones represented by the general formula (I) in high yields. The process according to the present invention will be further explained by way of the following examples. EXAMPLES Synthesis Example 1 [process variant (a)] 1-(2-chloro-6-methylphenyl)-5(4H)-tetrazolinone (0.63 g) and 4-dimethylaminopyridine (0.44 g) were dissolved in toluene (15 ml) and then dipropylcarbamoyl chloride (0.59 g) was added to the resulting solution, followed by a six-hour refluxing. After the completion of the reaction, the reaction product was purified according to a conventional procedure, so as to obtain the desired 1-(2-chloro-6-methylphenyl)-4-(N,N-dipropylcarbamoyl)-5(4H)-tetrazolinone (0.90 g), having a melting point (m.p.) in the range of from 66.5° to 68.5°C in a yield of 89% of the theory. N-selectivity: 100% (Figs. 3 and 4). Synthesis Example 2 [process variant (a)] 1-(2-chloro-6-methylphenyl)-5(4H)-tetrazolinone (0.63 g), potassium carbonate (0.50 g) and 4-dimethylamino-pyridine (0.037 g) were dissolved in acetonitrile (15 ml) and then dipropylcarbamoyl chloride (0.59 g) was added to the resulting solution, followed by a six-hour refluxing. After the completion of the reaction, the reaction product was purified according to a conventional procedure, so as to obtain the desired 1-(2-chloro-6-methylphenyl)-4-(N,N-dipropylcarbamoyl)-5(4H)-tetrazolinone (0.87 g), having a m.p. in the range of from 66.5° to 68.5°C in a yield of 86% of theory. N-selectivity: 100% (Figs. 3 and 4). Synthesis Example 3 [process variant (b)] 1-(2-chloro-6-methylphenyl)-5(4H)-tetrazolinone (2.11 g) and potassium carbonate (1.66 g) were mixed in acetonitrile (50 ml) and then dipropylcarbamoyl chloride (1.96 g) was added to the resulting solution, followed by a six-hour refluxing. After the completion of the reaction, the reaction product was purified according to the conventional procedure, so as to obtain a mixture (2.93 g) of the aimed N-carbamoyl product and the isomeric O-carbamoyl compound (Fig. 5). The N-selectivity of the reaction yielding this mixture turned out to be 71%. The resulting mixture and 4-dimethylamino-pyridine (0.11 g) were dissolved in acetonitrile (40 ml), followed by a six-hour refluxing. After the completion of the reaction, the reaction product was purified according to a conventional procedure, so as to obtain the desired 1-(2-chloro-6-methylphenyl)-4-(N,N-dipropylcarbamoyl)-5(4H)-tetrazolinone (2.51 g), having a m.p. in the range of from 66.5° to 68.5°C in a yield of 86% of theory. N-selectivity: 100% (Figs. 3 and 4). If desired, the two isomers contained in the above mixture can be separated and isolated in clean form by conventional methods, to determine their individual properties. Thus, the NMR- and IR-spectra of the O-carbamoyl isomer is shown in Figures 1 and 2, respectively, while the NMR- and IR-spectra of the N-carbamoyl isomer is shown in Figures 3 and 4, respectively. Further Examples : In analogous manner as described in Synthesis Examples 1-3, there can be obtained the following compounds shown in Table 1 which follows; for all listed compounds the N-selectivity proved to be 100% as in the case of the N-carbamoyl compound obtained in said foregoing Synthesis Examples 1-3 (such compound being also included in Table 1 as Example No. 15). Brief explanation of Figures 1-5: Figure 1 is a graph showing the NMR spectrum of 1-(2-chloro-6-methylphenyl)-5-(N,N-dipropylcarbamoyloxy)-tetrazole of the formula i.e. the "O-carbamoyl" isomer of 1-(2-chloro-6-methylphenyl)-4-(N,N-dipropylcarbamoyl)-5(4H)-tetrazolinone, the latter being described in Synthesis Examples 1-3 and also in Table 1 as Example No. 15. The "O-carbamoyl" isomer has been synthesized according to Synthesis Example 3, first step, then isolated from the initial mixture of the O-/N-isomers (by HPLC). Figure 2 is a graph showing the IR spectrum of the same "O-carbamoyl" compound (neat) as in Fig. 1. Figure 3 is a graph showing the NMR spectrum of 1-(2-chloro-6-methylphenyl)-4-(N,N-dipropylcarbamoyl)-5(4H)-tetrazolinone, according to the invention, as described in Synthesis Examples 1-3 and also in Table 1 as Example No. 15. Figure 4 is a graph showing the IR spectrum of the same compound (in nujol), according to the invention, as in Fig. 3. Figure 5 is a graph showing the NMR spectrum of a (71:29)-mixture of 1-(2-chloro-6-methylphenyl)-4-(N,N-dipropylcarbamoyl)-5(4H)-tetrazolinone and its "O-carbamoyl" isomer, said mixture being obtained according to the first step of Synthesis Example 3.

Claims: A process for selectively producing 1,4-disubstituted-5(4H)-tetrazolinones represented by the general formula: wherein R 1 represents C 1-12 alkyl, C 1-6 haloalkyl, C 2-8 alkoxyalkyl, C 2-8 alkylthioalkyl, C 3-8 cycloalkyl, C 3-8 alkenyl, C 3-8 haloalkenyl, C 3-8 alkynyl, or a group represented by the general formula wherein Ar represents unsubstituted phenyl, or a phenyl group having a substituent or substituents optionally selected from the group consisting of halogen, C 1-4 alkyl, C 1-4 haloalkyl, C 1-4 alkoxy,C 1-4 haloalkoxy, C 1-4 alkylthio, C 1-4 haloalkylthio, C 1-4 alkoxy-carbonyl, carboxy, optionally substituted phenoxy, optionally substituted heterocyclyl-oxy, methylene dioxy, halomethylene dioxy, ethylene dioxy, haloethylene dioxy, cyano, nitro and -NR 5 R 6 ; or Ar represents unsubstituted naphthyl, or a substituted naphthyl group having a substituent or substituents optionally selected from the group consisting of halogen, C 1-4 alkyl, C 1-4 haloalkyl, C 1-4 alkoxy, C 1-4 haloalkoxy, C 1-4 alkylthio, C 1-4 haloalkylthio, C 1-4 alkoxy-carbonyl, carboxyl, optionally substituted phenoxy, optionally substituted heterocyclyl-oxy, methylene dioxy, halomethylene dioxy, ethylene dioxy, haloethylene dioxy, cyano, nitro and -NR 5 R 6 ; or Ar represents a five- to seven-membered heterocyclic ring or their benzologues or their substituted derivatives having a substituent or substituents optionally selected from the group consisting of halogen, C 1-4 alkyl, C 1-4 haloalkyl, C 1-4 alkoxy, C 1-4 haloalkoxy, C 1-4 alkylthio, C 1-4 haloalkylthio, C 1-4 alkoxy-carbonyl, carboxy, optionally substituted phenoxy, optionally substituted heterocyclyl-oxy, methylene dioxy, halomethylene dioxy, ethylene dioxy, haloethylene dioxy, cyano, nitro and -NR 5 R 6 ; R 4 represents hydrogen or C 1-4 alkyl, R 5 and R 6 may be the same or different and represent hydrogen or C 1-4 alkyl, and n represents 0, 1, 2 or 3; and R 2 and R 3 each independently represents methyl, ethyl, n-propyl, isopropyl, n-(sec-,iso-, or tert-)butyl, n-pentyl, n-hexyl, trifluoromethyl, difluoromethyl, 2-chloroethyl, 2-fluoroethyl, 2,2,2-trifluoroethyl, 3-fluoropropyl, perfluoropropyl, perfluorohexyl, 2-methoxyethyl, ethoxymethyl, 2-ethoxyethyl, 2-propoxyethyl, 2-methylthioethyl, 3-methylthiopropyl, 2-ethylthioethyl, allyl, 2-(3-, 4-)butenyl, hexenyl, 3-chloroallyl, propargyl, methoxy, ethoxy, n-propoxy, isopropoxy, 3-chloroallyloxy, cyclopropyl, cyclopentyl, cyclohexyl, optionally substituted phenyl or benzyl, (wherein said substituents may be optionally selected from the group consisting of fluorine, chlorine, bromine, methyl, ethyl, n-propyl, isopropyl, tert-butyl, trifluoromethyl, methoxy, ethoxy, isopropoxy, difluoromethoxy, trifluoromethoxy, methylthio, ethoxy, isopropoxy, difluoromethoxy, trifluoromethoxy, methylthio, ethylthio, trifluoromethylthio, 2,2,2-trifluoroethylthio, cyano and nitro), or R 2 and R 3 together with the adjacent nitrogen atom may form piperidino, 2,6-dimethylpiperidino, morpholino, 2,6-dimethylmorpholino, thiomorpholino, 2,3-dihydroindolyl or perhydroindolyl, which process comprises (a) reacting a compound represented by the general formula (II), wherein R 1 has the same meaning as mentioned above, with a compound represented by the general formula (III), wherein R 2 and R 3 have the same meanings as mentioned above, in the presence of a catalytic (sub-stoichiometric) amount of 4-dimethylamino-pyridine and optionally in the presence of a diluent and of an additional acid-binder selected from the group consisting of inorganic bases (such as carbonates and bicarbonates of alkali metals) and organic bases (such as tertiary amines, pyridines, DABCO and DBU), at a temperature of from +15°C to +150°C, or (b) reacting a compound represented by the above-mentioned general formula (II) with a compound represented by the above-mentioned general formula (III), optionally in the presence of a diluent and of an acid-binder other than 4-dimethylamino-pyridine (as defined under process variant (a) above), to obtain a mixture consisting of a tetrazolinone represented by the above-mentioned general formula (I) and a compound represented by the general formula (IV), wherein R 1 , R 2 and R 3 have the same meanings as mentioned above, (first step) followed by reacting said obtained mixture with a catalytic (sub-stoichiometric) amount of 4-dimethylamino-pyridine, optionally in the presence of a diluent, at a temperature of from +15°C and +150°C, thereby effecting conversion of the compound(s) of formula (IV) to the desired isomeric compound(s) of formula (I) (second step), employing in both process variants (a) and (b) the 4-dimethylamino-pyridine as catalyst in amounts of from 0.01 to 0.5 mols per mol of the compound of formula (II). The process according to claim 1, wherein the process variant (a) is carried out at a temperature of from 50°C to 130°C. The process according to claim 1, wherein the process variant (b) is carried out at a temperature of from 50°C to 130°C.

Inventors: NARABU SHIN-ICHI, WATANABE YUKIYOSHI, YANAGI AKIHIKO, NARABU, SHIN-ICHI, WATANABE, YUKIYOSHI, YANAGI, AKIHIKO
Applicants: BAYER AGROCHEM KK, NIHON BAYER AGROCHEM K.K.
Application year: 1994
Main classification: C07D257
IPC codes: C07D405, C07D257, C07D417, C07D401, C07D409, C07D403, C07D413